Compliant Assembly Variation Analysis of Composite Structures Using the Monte Carlo Method with Consideration of Stress-Stiffening Effects

The application of an interference fit in the assembly process of thin-walled aerospace composite parts is prone to stress stiffness effects, namely the structural stiffness change caused by the inplate-induced stress. Limited applicability has been available in this regard when using the compliant assembly analysis based on the stiffness-invariant assumption, such as the method of influence coefficient. In addition, these materials possess a hierarchical structure that necessitates the use of material uncertainty in the analysis. However, it is costly and complicated to develop uncertainty analysis and modeling calculations at different scales. In this study, a deviation propagation model of the composite structure (DPMoCS) considering the stress-stiffening effect is proposed to improve the analysis efficiency. Based on the geometric nonlinear theory, the factors of interest affecting the stress-stiffening effect in the interference assembly of a thin-walled composite material are investigated, which are the material elastic and stress field. Our simulations are integrated with material uncertainty quantization and propagation across scales to characterize the uncertainty of the factors of interest as well as reduce the computational cost based on the equivalent model. The method is combined with the Monte Carlo-based stochastic finite element method and applied to the assembly analysis of a composite panel subassembly. The results show that consideration of the stress-hardening effect has a significant effect on the DPMoCS and affects the assembly accuracy as the fiber layup angle deviation increases.